DE60107412T2 - Process for the production of skin-free PVC - Google Patents

Abstract

Process for preparation of polyvinyl chloride (PVC) comprising the steps of: mass polymerizing vinyl chloride monomer in the presence of at least one oil soluble emulsifier and at least one initiator in a first reactor having an agitator stirring with high shear until a desired conversion is reached; transferring the content of the first reactor into at least one second reactor which has been charged with demineralized water and at least one water soluble emulsifier; and polymerizing the mixture in the second reactor having an agitator stirring with shear lower than in the first reactor until a desired conversion is reached. <IMAGE>

Description

The The present invention relates to a process for the preparation of Polyvinyl chloride (PVC), in particular a process for the preparation a skin-free polyvinyl chloride.

Various Procedure for the production of polyvinyl chloride are known in the art.

US 3,522,227 discloses a process for bulk polymerization of vinyl chloride monomer to increase the density of the prepared granules, wherein the polymerization is conducted in a variety of stages under similar pressure, temperature and catalytic conditions, comprising precursor processing to about 7-12% completeness of the polymerization, accompanied by high vortex stirring, and final stage processing in the absence of high turbulence to a selected polymerization end point under relatively mild agitation applied peripherally to the polymer-containing mass. The polymerization is carried out without the presence of water.

US 3,687,919 discloses a process for polymerizing ethylenic monomers capable of being polymerized in bulk to form spherical particles of controlled size distribution, wherein the polymerization mixture is stirred in a first reaction step with a high stirring speed and then to a second reactor transferred, which is provided with milder agitation. The polymerization is carried out without the presence of water.

However, the bulk polymerization processes are the US 3,522,227 and US 3,687,919 Low productivity processes and therefore less economical than standard polymerisation processes of vinyl chloride monomer, which are based on suspension technology.

US 3,706,722 discloses a process for polymerizing substantially water-insoluble polymerizable ethylenically unsaturated liquid monomer first as an initial continuous phase consisting of monomer in the presence of a catalyst which is soluble in the monomer. The monomer is polymerized with agitation to provide conversion of the monomer to the polymer up to about 5-20%, followed by addition of sufficient water to the monomer-polymer mixture with stirring and in the presence of a water-soluble suspending agent to effect the reaction invert, making water the continuous phase. The mixture is then polymerized to the desired conversion. The polymerization according to US 3,706,722 can be carried out in the presence of a surface active agent which is solubilized in the monomer and is carried out in only one reactor, wherein the stirring speed of the stirrer in the reactor is not changed. It is known to those skilled in the art that the process of the US 3,706,722 is a process of low productivity and reactor fouling occurs to a considerable degree during the polymerization. Therefore, the procedure is the US 3,706,722 less economical than a process for the production of polyvinyl chloride, which is based on a standard suspension technology.

US 4,775,702 discloses an aqueous phase inversion process for producing skin-free and crosslinked PVC resins comprising polymerizing vinyl chloride monomer together with at least one crosslinking agent, the process being carried out first with the monomer phase as the continuous phase, and from about 1% to about 10% Conversion of the monomer to polymer is added to water to invert the process so that the aqueous phase is the continuous phase and the monomer phase is a discontinuous phase.

It is therefore an object of the present invention, a method to provide for the production of polyvinyl chloride, which is the Disadvantages of the prior art overcome, in particular a To provide a method which skin-free polyvinyl chloride with high productivity on an economic Fashion manufactures.

• – Massepolymerisation von Vinylchloridmonomer in der Gegenwart wenigstens eines öllöslichen Emulgators und wenigstens eines Initiators in einem ersten Reaktor mit hoher Scherrührung mit einer schnellen Rührgeschwindigkeit in einem Bereich von 100–1.500 rpm, bis ein gewünschter Umsatz in dem Bereich von 1–15 % erreicht wird;
• – Überführen des Inhalts des ersten Reaktors in wenigstens einen zweiten Reaktor, welcher mit entmineralisiertem Wasser und wenigstens einem wasserlöslichen Emulgator befüllt worden ist; und
• – Polymerisieren der Mischung in dem zweiten Reaktor mit einer Rührung mit kleinerer Scherung als die Rührung in den ersten Reaktor, bis ein gewünschter Umsatz in dem Bereich von 60–100 % erreicht wird.

The object of the present invention is achieved by a process for the preparation of polyvinyl chloride (PVC), which comprises the steps:

• Bulk polymerization of vinyl chloride monomer in the presence of at least one oil-soluble emulsifier and at least one initiator in a first high shear agitation reactor at a fast stirring speed in a range of 100-1,500 rpm until a desired conversion in the range of 1-15% is achieved;
• Transferring the contents of the first reactor into at least one second reactor which has been charged with demineralised water and at least one water-soluble emulsifier; and
• - Polymerizing the mixture in the second reactor with a smaller shear stir than stirring in the first reactor until a desired conversion in the range of 60-100% is achieved.

According to the present Invention is the stirring speed in the first reactor preferably in the range 750-1,200 rpm, and the stirring speed in the second reactor is in the range of about 75-500 rpm, preferably 95-350 rpm, and the second reactor is about 2-2.5 times larger than the first reactor.

Prefers For example, the temperature in the first reactor is in the range of 55-75 ° C, more preferably 65 ° C, and the temperature in the second reactor is in the range of about 45-75 ° C, more preferably 50-70 ° C.

According to the present Invention provides a method wherein the turnover in the first reactor is in the range of about 1-15%, preferably 7-10%, and the conversion in the second reactor in the range of about 60-100%, preferably 75-85 % lies.

Further, the volume of the first reactor in the range of 1 may be l to 75 m ^3, preferably in the range of 25-75 m ³ lie, and the volume of the second reactor may be l to 150 m in the range of about 8 ^3, preferably be in the range of 50-150 m ³ .

Prefers For example, a first reactor with up to five second reactors may be used and the first reactor may be above the second reactor can be arranged and can through a solid pipe or a blow-off be connected to the second reactor.

The oil-soluble emulsifier may sorbitan monolaurate, sorbitan palmitate, sorbitan tristearate, sorbitan trioleate, preferably sorbitan palmitate, or various sucrose ester mixtures of sucrose distearate, monostearate, tristearate, dipalmitate, tetrastearate, pentastearate, hexastearate, heptastearate or octastearate, are preferred Mixtures of hexastearate, pentastearate and heptastearate with a hydrophilic / lipophilic balance value between 1-15, preferably 1-10. The oil-soluble emulsifier can be in the amount of 100-10,000 Ppm by weight, based on the weight of the vinyl chloride monomer be used. The oil-soluble emulsifier may also be selected from sucrose esters.

Of the Initiator can be selected are selected from the group comprising di-2-ethylhexyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-butyl peroxyneoheptanoate, tert-butyl peroxyneodecanoate, with di-2-ethylhexyl peroxydicarbonate being preferred is.

Of the Initiator is based in an amount of 100-1,000 ppm by weight on the weight of the vinyl chloride monomer.

Of the water-soluble Emulsifier can be selected are selected from the group comprising alkyl or hydroxyalkyl cellulose ethers, methyl cellulose and methylhydroxypropylcellulose, with methylhydroxypropylcellulose being preferred is. It is understood that the the latter emulsifier group is intended merely as an illustration is and not in a limiting sense.

The water-soluble Emulsifiers can in an amount of 500-5,000 Ppm by weight, based on the weight of the vinyl chloride monomer, be used.

According to the present Invention is the weight ratio from water to monomer in the second reactor in the range of 1.0-1.5 to 1.

optional can the second reactor in addition be filled with vinyl chloride monomer and / or its comonomers.

It is obvious that beside Vinyl chloride at least one comonomer in the first and / or second Reactor may be present. The comonomers copolymerizable with vinyl chloride are as they are referred to in this invention include all Comonomers, which are known copolymerizable with vinyl chloride such as vinyl bromide, vinylidene chloride and the like.

Surprisingly, it has been found that by using the process according to the present invention polyvinyl chloride can be prepared which is skin-free and of good quality and which can be produced with high productivity. This is due to the specific variation of the suspensi on-technology for producing polyvinyl chloride, namely bulk prepolymerization in a high shear agitation reactor, followed by suspension polymerization in a second larger, lower shear agitation reactor than in the first reactor. By following the procedure of the present invention, reactor fouling can be prevented. The process of the present invention is a process that results in a clean reactor.

Further Advantages and features of the present invention will become apparent in the following Description in greater detail considering explains the drawing, which consists of only one figure, which is a schematic View of the reactor system of the present invention.

According to the figure, a first reactor 1 is provided with an oil-soluble emulsifier supply line 2 and an initiator, and with a second supply line 3 for supplying vinyl chloride monomer. The first reactor 1 has, for example, a volume of 25 to 75 m ³ . Within the reactor 1, a stirrer 4 is arranged. According to the figure, the reactor 1 is connected to five second reactors 5 via line 6. The conduit 6 may be a solid pipe or a blow-off conduit. Preferably, the second reactors 5 are arranged below the first reactor 1 and have a volume of about 50 to 150 m ³ . Within the second reactors 5, a stirrer 7 is provided in each case. Further, each reactor 5 is provided with a supply line 8 for supplying the reactor 5 with demineralized water and water-soluble emulsifier. Optionally, another supply line (not shown) may be provided to the second reactor 5 for providing further vinyl chloride monomer or comonomer to the reactor 5.

The Method according to the present invention Invention is carried out as follows: To the reactor 1 is a Recipe quantity of the oil-soluble Emulsifier added. Then the reactor 1 is closed and pulled full vacuum, the Reactor 1 is then purged with nitrogen and full vacuum is again drawn. Subsequently the reactor 1 is purged with vinyl chloride monomer and made to atmospheric Vented pressure. The vinyl chloride monomer is then added to the reactor 1. Subsequently, will the stirrer 4 with a stirring speed started from about 750 to 1200 rpm and the reactor 1 is on the desired Temperature warmed, which is in the range of about 60 to 70 ° C.

simultaneously is a second reactor 5 with the recipe amount of water and the water-soluble emulsifier filled. The reactor 5 is closed and full vacuum is drawn, whereupon the reactor 5 is purged with nitrogen and full vacuum again is pulled. Subsequently the reactor 5 is rinsed again with vinyl chloride monomer and to atmospheric Vented pressure. Optionally, further vinyl chloride monomer may be added to the reactor 5. After all becomes the stirrer 7 with a stirring speed started in the range of 95 to 350 rpm, and the reactor 5 becomes to the desired Temperature in the range of 50 to 70 ° C heated.

As soon as both reactors 1 and 5 their desired Temperatures, the initiator is in the first reactor 1 is injected and the polymerization in reactor 1 is carried out until the desired one Sales has been achieved. Subsequently, the content of the first Reactor 1 transferred to the second reactor 5 and the valves (not shown) between the two reactors 1, 5 are closed and the reactor 1 is vented. The first reactor 1 is purged with nitrogen and can then be inspected and cleaning to be opened. The polymerization proceeds now in the second reactor 5, and when the pressure in the reactor 5 drops to a certain size is injected a stopper to stop the polymerization. Not reacted monomer is discharged from the reactor 5 and the contents of the reactor 5 is at 90 ° C for 10 Minutes stripped. After all the reactor 5 is cooled and its contents can be taken.

in the Subsequently, the method of the present invention will further be understood by means of Examples illustrated.

example 1

To a 4.35 liter reactor the following ingredients are added:
3.38 kg of vinyl chloride monomer, 10.14 g of oil-soluble emulsifier Span 80. The stirrer is started at 1200 rpm and the mixture is heated to 65 ° C. Then 6.76 g of di-2-ethylhexylperoxydicarbonate are injected.

After a 20 minute reaction time, the contents of the reactor are dropped to a 10.2 liter reactor previously charged with 5.07 kg of demineralized water and 105.6 g of hydroxypropyl methylcellulose. The previously introduced materials were heated to 58.5 ° C with a stirring speed of 350 rpm. This reaction mixture can react for a total reaction time of 315 minutes. The unreacted vinyl chloride monomer in the reactor is then drained off and the remaining material is dewatered and dried. The polyvinyl chloride obtained in Example 1 has the properties outlined in Table 1 below.

Table 1

Example 2

To a 4.35 liter reactor the following ingredients were added:
3.38 kg of vinyl chloride monomer, 16.90 g of oil-soluble emulsifier Span 40. The stirrer is started at 1200 rpm and the mixture is heated to 65.degree. Then 4.23 g of di-2-ethylhexylperoxydicarbonate are injected.

To a 17-minute drive Reaction time, the contents of the reactor become a 10.2 liters Reactor toppled, the previously 5.07 kg demineralized water and 140.83 g hydroxyproylmethyl cellulose been filled was. The previously introduced Materials are 58.5 ° C with a stirring speed heated by 300 rpm Service. This reaction mixture may be for a total reaction time respond by 380 minutes. The unreacted vinyl chloride monomer in the reactor is then drained and the remaining material is drained and dried.

The Polyvinyl chloride obtained in Example 2 has the properties outlined in Table 2 below.

Table 2

Example 3

To To a 4.35 liter reactor, the following ingredients were added: 3.38 kg of vinyl chloride monomer, 13.52 g of oil-soluble emulsifier Span 40. The stirrer is started at 1200 rpm and the mixture is heated to 65 ° C. Then 5.07 g of di-2-ethylhexyl peroxydicarbonate injected.

To a 20-minute drive Reaction time, the contents of the reactor become a 10.2 liters Reactor toppled, the previously 5.07 kg demineralized water and 140.83 g hydroxypropyl methylcellulose been filled was. The previously introduced Materials are 58.5 ° C with a stirring speed heated by 300 rpm Service. This reaction mixture may be for a total reaction time respond by 420 minutes. The unreacted vinyl chloride monomer in the reactor is then drained, and the remaining material is drained and dried.

The Polyvinyl chloride obtained in Example 3 has the properties outlined in Table 3 below.

Table 3

Example 4

To To a 4.35 liter reactor, the following ingredients are added: 2.55 kg of vinyl chloride monomer, 9.87 g of oil-soluble emulsifier S-170 sucrose ester. The stirrer is started at 900 rpm and the mixture is heated to 65 ° C. Then 3.18 g of di-2-ethylhexyl peroxydicarbonate injected.

To a 45-minute drive Reaction time, the contents of the reactor are toppled to a 10.2 liter reactor, the previously with 4.95 kg of demineralized water and 274.55 g of hydroxypropylmethylcellulose been filled was. The previously introduced Materials are 58.5 ° C with a stirring speed heated by 300 rpm Service. This reaction mixture may be for a total reaction time respond by 330 minutes. The unreacted vinyl chloride monomer in the reactor is then drained, and the remaining material is drained and dried.

The Polyvinyl chloride obtained in Example 4 has the properties outlined in Table 4 below.

Table 4

The Features described in the foregoing description, in the claims and / or in the accompanying Drawing can be disclosed, both separately and in any combination thereof, material for Implementation of the invention in a variety of forms.

Claims (16)

Process for the preparation of polyvinyl chloride (PVC), which comprises the steps: Bulk polymerization of vinyl chloride monomer in the presence of at least one oil-soluble emulsifier and at least an initiator in a first reactor with a stirrer, the with a high shear in a range of 100 - 1500 rpm stirred, until a desired one Sales in the range of 1 - 15% is achieved; - Transfer of the Contents of the first reactor in at least one second reactor, which with demineralized water and at least one water-soluble Emulsifier filled has been; and - Polymerize the mixture in the second reactor with a stirrer, which sheared stirred, which is smaller than in the first reactor until a desired one Sales in the range of 60 - 100% is reached. Method according to claim 1, characterized in that that the Stirring speed in the first reactor is in the range of 750-1200 rpm and the stirring speed in the second reactor in the range of about 75-500 rpm, preferably 95-350 rpm is. Method according to claim 1 or 2, characterized that the second reactor 2-2.5 times greater than the first reactor is. Method according to one of the preceding claims, characterized characterized in that Temperature in the first reactor in the range of 55-75 ° C, preferred 65 ° C, is and the temperature in the second reactor in the range of 45-75 ° C, preferred 50 - 70 ° C, is. Method according to one of the preceding claims, characterized characterized in that Conversion in the first reactor is in the range of 7 - 10% and the conversion in the second reactor is in the range of 75-85%. Process according to one of the preceding claims, characterized in that the volume of the first reactor is in the range from 1 liter to 75 m ³ , preferably in the range from 25 to 75 m ³ , and the volume of the second reactor ranges from 8 liters to 150m ³ , preferably in the range of 50-150m ³ . Method according to one of the preceding claims, characterized characterized in that a first reactor with up to five second reactors is used. Method according to one of the preceding claims, characterized characterized in that first reactor is arranged above the second reactor and through a solid pipe or a blow-off line with the second reactor connected is. Method according to one of the preceding claims, characterized characterized in that the oil-soluble emulsifier selected is made from sorbitan or sucrose esters or mixtures thereof. Method according to claim 9, characterized in that that the oil-soluble emulsifier in an amount of 100 to 10,000 ppm by weight, based on the Weight of vinyl chloride monomer is used. Method according to one of the preceding claims, characterized characterized in that Initiator selected is selected from the group comprising di-2-ethylhexyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-butyl peroxyneoheptanoate, tert-butyl peroxyneodecanoate, with di-2-ethylhexyl peroxydicarbonate being preferred becomes. Method according to claim 11, characterized in that that the Inititator in an amount of 100 - 1,000 ppm by weight, based on the weight of the vinyl chloride monomer. Method according to one of the preceding claims, characterized characterized in that water-soluble Emulsifier selected is selected from the group comprising alkyl or hydroxyalkyl cellulose ethers, Methyl cellulose and methyl hydroxypropyl cellulose, wherein methyl hydroxypropyl cellulose is preferred. Method according to claim 13, characterized in that that the water-soluble Emulsifier in an amount of 500 - 5,000 ppm by weight, based on the weight of the vinyl chloride monomer. Method according to one of the preceding claims, characterized characterized in that weight ratio from water to monomer in the second reactor in the range of 1.0 - 1.5 to 1. Method according to one of the preceding claims, characterized characterized in that second reactor in addition filled with vinyl chloride monomer becomes.